Solid agent for eliminating soot and in particular tars, and method for making same and uses thereof

ABSTRACT

Solid agent for destroying soot and tars, which includes, aggregated and as base constituents: (a) an agent which is active with respect to soot and tars, (b) plant waste and (c) a binding agent, characterized in that the agent which is active with respect to soot and tars is present in a proportion of greater than 40% (dry weight).

[0001] The present invention relates to a solid agent for destroying soot and in particular tars, and to its process of manufacture and to its uses.

[0002] The invention thus relates to the chemical cleaning of combustion devices and flues which are contaminated by deposits of soot and in particular deposits of tars, with the aim of preventing possible chimney fires.

[0003] Provision has already been made to prepare solid bodies for destroying soot and tars. Thus, the document FR-A-2 554 458 discloses a combustible complex using small proportions of heavy metal compounds. The document FR-A-2 749 855 discloses a chimney-cleaning agent, mainly in the log form, which includes in particular wood particles, a binder, such as paraffin wax, and an agent which destroys soot. This chimney-cleaning agent is mainly intended to be used alone, in a nonactive fireplace, thus without other combustible undergoing combustion, that is to say in an “autonomous” way.

[0004] However, it has been found that, whatever the merit of the latter agent, the effect of a single chimney-cleaning log, used in an autonomous way, in heavily fouled or large chimneys may be insufficient, necessitating the burning of several logs simultaneously or the repetition of the chimney-cleaning operation.

[0005] Without wishing to be restricted to a specific explanation, it is believed that, under the particularly difficult conditions mentioned above, the tars are not sufficiently hot, in particular because of their thickness, for rapid and complete chimney-cleaning to be obtained with a single log.

[0006] There is therefore a place in the art for a chimney-cleaning agent of increased activity which can be used more particularly in the difficult cases mentioned above.

[0007] Furthermore, the use has been known for a long time of products known as “chimney-cleaning powders”, which are introduced into active fireplaces. This use presents a number of problems as regards its implementation:

[0008] difficulties in precisely measuring out the amount of powder to be introduced into the fireplace to produce the desired maximum effect in destroying the soot and tars (measuring out is generally carried out in a very traditional way “with a tablespoon”);

[0009] excessively high speed of the diffusion of the fumes resulting from the active products, which is reflected by a greatly reduced effectiveness of the treatment.

[0010] The need has thus made itself felt to provide the consumer with a novel product corresponding to a two-fold objective:

[0011] first, effective use under difficult conditions (fouled or large chimneys);

[0012] secondly, great accuracy in measuring out active products necessary for the treatment, the novel product very advantageously replacing chimney-cleaning powders while additionally introducing the decisive advantage of a prolonged action of the active products over several hours.

[0013] The present invention is thus based on a novel concept, that of producing a solid body, such as a log, including, in aggregated form and as base constituents, more than 40% by weight of agent which is active with respect to soot and tars, the remainder including combustible particulate plant waste and a binding agent.

[0014] According to the present invention, the said binder is preferably an organic binder derived from carbon, which makes it possible to improve the combustibility of the log.

[0015] The invention also relates to the use of this solid body, which consists in placing it in an active fireplace, preferably in contact with hot embers, more particularly on a bed of incandescent embers or embers close to incandescence, under combustion conditions which are kept slow. By virtue of the relatively high temperature of the embers, the solid body, for example in the form of one or more logs, will be subjected to slow deagglomeration/combustion/volatilization and the fumes given off will efficiently treat the tars of the combustion device and/or of the chimney, in particular if the device and/or chimney are large or heavily fouled. However, the operation in a fireplace under excessively strong combustion will be avoided, in order to avoid excessively rapid entrainment of the active components of the solid body.

[0016] The agent which is active with respect to tars will represent approximately 41 to 90% by weight of the solid body. The remainder will advantageously be composed of particulate plant waste, such as wood waste, and of binding agent, preferably combustible binding agent, for example paraffin wax and/or stearic acid. Thus, the plant waste can represent 5 to 50% and the binder 5 to 50% by weight of the solid body, the total with the active agent representing 100%. These values are expressed as dry weight.

[0017] Secondary constituents can be present in addition to the essential constituents above, for example colorants, fragrances, water of hydration or from moisture, combustion additives, and the like. These secondary constituents can represent up to 50 parts by weight per 100 parts by weight of the three base constituents above. However, water in excess of more than 20 parts per 100 parts (dry weight) of the three base constituents will be avoided and the operation will preferably be carried out with constituents which are as dry as possible, in particular as regards the wood particles.

[0018] The active agent is advantageously composed of one or more alkali metal and/or alkaline earth metal and/or ammonium and/or amine compounds, preferably salts of one or more of these metals. Preference will be given to the salts for which at least one of the constituent ions is volatile on contact with embers. Thus, the ammonium, amine, chloride, acetate, formate, carbonate, sulphite and nitrate ions are regarded as relatively volatile in the context of the invention and the salts which comprise them will therefore be preferred.

[0019] Mention may be made, as salts which can be used in particular, of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, sodium nitrate, potassium nitrate, calcium nitrate and/or magnesium nitrate, and ammonium chloride, phosphate, sulphate and/or nitrate. However, excessively high proportions (for example 10% or more) of ammonium nitrate will be avoided for obvious reasons of safety.

[0020] Advantageously, at least 50% of the salts used will be salts having a volatile ion.

[0021] In order to aggregate together the various constituents, it is possible to compress them under cold conditions, for example in a press, the binder then being, like the other constituents, in the form of solid particles. However, it is preferable to use the binder in the molten form or in the form dissolved in a solvent which can subsequently be removed, the other constituents being employed in the solid state.

[0022] Thus, paraffin wax and stearic acid can advantageously be used in the molten state. It is then possible to operate under hot conditions in a mould.

[0023] Nonlimiting examples of the invention are given below, which can be carried out in order to manufacture solid bodies, for example logs, according to the invention:

[0024] Log No. 1 (as dry weight): 15% of sodium chloride, 25% of ammonium chloride, 5% of sodium nitrate, 5% of ammonium nitrate, 30% of paraffin wax and 20% of wood sawdust. The mixing is carried out under hot conditions with the molten paraffin wax, in a mould, with subsequent cooling and removal from the mould. Unit weight of a log: 1.5 kg.

[0025] Log No. 2 (as dry weight): 20% of ammonium sulphate, 20% of sodium chloride, 10% of calcium chloride, 20% of paraffin wax (or of stearic acid) and 30% of wood sawdust. Preparation under hot conditions as above. Unit weight of a log: 1.25 kg.

[0026] Log No. 3 (as dry weight): 10% of ammonium phosphate, 20% of ammonium chloride, 12% of ammonium sulphate, 5% of ammonium nitrate, 5% of ammonium acetate, 24% of wood sawdust and 24% of paraffin wax. Preparation under cold conditions in a press. Unit weight of a log: 2 kg.

[0027] The dimensions of particles of plant material are, for example, in the range from 0.1 mm to 10 mm, as are those of the particles of binder, if the latter is used in the solid state, such as, for example, with paraffin wax.

[0028] The salts are also advantageously used in the crystalline or noncrystalline solid state.

[0029] For use, the operation is carried out in a preheated fireplace, retaining a bed of embers, and the solid body, for example a log according to the invention, is placed on these embers. It may be advantageous to reduce the draught in order to avoid intense combustion with strong flames. The solid mass will gradually disintegrate with the release of the active materials which act on the tars, which will disintegrate and/or be rendered inactive or not very active with respect to possible ignition.

[0030] A log according to the invention was prepared with a total weight of 1.2 kg; this log contained 500 g of active products as defined above, 280 g of wood sawdust and 420 g of paraffin wax. This log was placed on embers in a fireplace. It began to burn and combustion was continued for approximately 1 hour, giving off, in the form of fumes, the active products present in the log. After the end of combustion, emission of the fumes resulting from the active products was continued, under the effect of the heat given off by the bed of embers, for a duration of approximately 3 hours.

[0031] At the end of this period of time, the block was reduced to fine dust, having thus diffused all its active products. Approximately a week later, it was found that the particles of carbonaceous matter (soot and tars) which were present in the chimney pipe had completely disintegrated, these particles, reduced to the powder form, falling into the fireplace, clearing the chimney pipe. These tests show the effective nature of the logs according to the invention in removing the soot which is deposited in chimney pipes, thus making it possible to avoid possible chimney fires. 

1. Solid agent for destroying soot and tars, which includes, aggregated and as base constituents: (a) an agent which is active with respect to soot and tars, (b) plant waste and (c) a binding agent, characterized in that the agent which is active with respect to soot and tars is present in a proportion of greater than 40% (dry weight).
 2. Agent according to claim 1, including, as base constituents, 41 to 90% by weight of agent which is active with respect to soot and tars, 5 to 50% of plant waste and 5 to 50% of binder, the proportions of these constituents being chosen so that the total represents 100% of the base constituents (dry weight).
 3. Agent according to claim 1 or 2, including, as base constituents, 45 to 75% of agent which is active with respect to soot and tars, 10 to 30% of plant waste and 10 to 30% of binder, the total representing 100% of the base constituents (dry weight).
 4. Agent according to one of claims 1 to 3, in which the binder is an organic binder derived from carbon.
 5. Agent according to one of claims 1 to 3, in which the binder is paraffin wax or stearic acid.
 6. Agent according to one of claims 1 to 5, in which the plant waste is wood waste.
 7. Agent according to one of claims 1 to 6, in which the active agent is composed of one or more alkali metal and/or alkaline earth metal and/or ammonium and/or amine compounds.
 8. Agent according to claim 7, in which the active agent is a salt for which at least one of the constituent ions is relatively volatile on contact with hot embers.
 9. Agent according to claim 8, in which the active agent is chosen from sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, sodium nitrate, potassium nitrate, calcium nitrate, magnesium nitrate, ammonium chloride, ammonium phosphate, ammonium sulphate and/or ammonium nitrate.
 10. Process for the manufacture of an agent according to one of claims 1 to 9, which consists in aggregating together the three base constituents, optionally with secondary constituents, in the solid state or by melting the binder and subsequent cooling or by use of active agent and of solid plant waste, the binder being dissolved in a solvent which is subsequently removed.
 11. Use of an agent according to one of claims 1 to 9, which consists in placing it on hot embers, in particular embers under slow combustion conditions, and in leaving the said agent to slowly disintegrate on contact with the hot embers. 